Apparatus and method for selecting frequency band

ABSTRACT

A switching circuit is provided. The switching circuit includes at least one Surface Acoustic Wave (SAW) filter, a Single-Pole n Throw (SPnT) switch connected to an input port of each of the at least one SAW filter, and a Dual-Pole n Throw (DPnT) switch connected to an output port of each of the at least one SAW filter.

PRIORITY

This application claims the benefit under 35 U.S.C. § 119(a) of a Koreanpatent application filed in the Korean Intellectual Property Office onSep. 3, 2012 and assigned Serial No. 10-2012-0097362, the entiredisclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and method for selecting afrequency band.

2. Description of the Related Art

A radio communication system may provide various high-speedlarge-capacity services to Mobile Stations (MSs), and may be a Long-TermEvolution (LTE) mobile communication system, a Long-Term EvolutionAdvanced (LTE-A) mobile communication system, an Evolved Packet System(EPS), an Institute of Electrical and Electronics Engineers (IEEE)802.16m communication system and any other suitable and/or similar radiocommunication system. As described above, radio communication systemshave evolved, along with MSs that have evolved to receive high-speedlarge-capacity services, and more specially to receive services throughvarious frequency bands.

FIG. 1 illustrates an internal structure of an MS in a radiocommunication system according to the related art.

Referring to FIG. 1, an MS includes an antenna (ANT) and a Front EndModule (FEM) 100. The FEM 100 includes a switch, such as a Single-Pole 7Throw (SP7T) switch 111 and a plurality of filters, such as SurfaceAcoustic Wave (SAW) filters which are shown as first through seventh SAWfilters 113, 115, 117, 119, 121, 123 and 125. Each of the SAW filters113 to 125 may be used for a Transmission (TX) jammer rejection, and mayperform a filtering operation corresponding to a preset frequency band.The SAW filters 113 to 125 have paths connected to a Radio FrequencyIntegrated Circuit (RFIC) (not shown) per a related frequency band.

Signals output from the SAW filters 113 to 125 may be integrated so thatan MS facilitates receiving services through various frequency bands.Further, a case of integrating the signals output from the SAW filters113 to 125 may occur in order to decrease the unit cost of production ofthe MS and to minimize a hardware space or size of the MS. If thesignals output from the SAW filters 113 to 125 are integrated, then theunit cost of production of the MS may be decreased and the hardwarespace of the MS may be minimized since the paths on which the SAWfilters 113 to 125 and the RFIC are connected one to one. However, FEMsof the related art may not integrate signals output from SAW filters.

Therefore, a need exists for a system and method for integrating thesignals output from the SAW filters.

The above information is presented as background information only toassist with an understanding of the present disclosure. No determinationhas been made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the present invention.

SUMMARY OF THE INVENTION

Aspects of the present invention are to address at least theabove-mentioned problems and/or disadvantages and to provide at leastthe advantages described below. Accordingly, an aspect of the presentinvention is to provide a switching circuit and method for selecting afrequency band.

Another aspect of an exemplary embodiment of the present invention is toprovide a Radio Frequency (RF) hardware and method for selecting afrequency band.

Furthermore, another aspect of an exemplary embodiment of the presentinvention is to provide a Front End Module (FEM) and method forselecting a frequency band.

Still another aspect of an exemplary embodiment of the present inventionis to provide a signal reception apparatus and method for selecting afrequency band.

Still another aspect of an exemplary embodiment of the present inventionis to provide at least one of a switching circuit, an RF hardware, aFEM, and a signal reception apparatus and method for selecting afrequency band by combining output signal from filters.

Still another aspect of an exemplary embodiment of the present inventionis to provide a switching circuit, an RF hardware, a FEM, and a signalreception apparatus and method for selecting a frequency band bycombining output signal from filters thereby satisfying a thresholdfrequency band attenuation requirement value.

Still another aspect of an exemplary embodiment of the present inventionis to provide at least one of a switching circuit, an RF hardware, aFEM, and a signal reception apparatus and method for selecting afrequency band by combining output signal from filters therebysatisfying a threshold isolation requirement value.

In accordance with one aspect of the present invention, a switchingcircuit for selecting a frequency band is provided. The switchingcircuit includes at least one Surface Acoustic Wave (SAW) filter, aSingle-Pole n Throw (SPnT) switch connected to an input port of each ofthe at least one SAW filters, and a Dual-Pole n Throw (DPnT) switchconnected to an output port of each of the at least one SAW filter.

In accordance with another aspect of the present invention, a switchingcircuit for selecting a frequency band is provided. The switchingcircuit includes a plurality of SAW filters; a SPnT switch connected toan input port of each of the a plurality of SAW filters; a first DPnTswitch connected to an output port of at least one of the a plurality ofSAW filters, and a second DPnT switch connected to an output port of atleast one of the a plurality of SAW filters except for the at least oneSAW filter connected to the first DPnT switch from among the a pluralityof SAW filters.

In accordance with further another aspect of the present invention, aswitching circuit for selecting a frequency band is provided. Theswitching circuit includes a plurality of SAW filters, a first SPnTswitch connected to an input port of each of the a plurality of SAWfilters, a second SPnT switch connected to an output port of at leastone of the a plurality of SAW filters, and a third SPnT switch connectedto an output port of at least one of the a plurality of SAW filtersexcept for the at least one SAW filter connected to the second SPnTswitch from among the a plurality of SAW filters.

In accordance with still another aspect of the present invention, aswitching circuit for selecting a frequency band is provided. Theswitching circuit includes a plurality of SAW filters, a first SPnTswitch connected to an input port of at least one of the plurality ofSAW filters, a second SPnT switch connected to an input port of at leastone of the plurality of SAW filters except for the at least one SAWfilter connected to the first SPnT switch from among the plurality ofSAW filters, a SPDT switch connected to an input port of the first SPnTswitch and input port of the second SPnT switch; and a combinerconnected to an output port of each of the plurality of SAW filters.

In accordance with still another aspect of the present invention, aswitching circuit for selecting a frequency band is provided. Theswitching circuit includes a plurality of SAW filters, a first SPnTswitch connected to an input port of at least one of the plurality ofSAW filters, a second SPnT switch connected to an input port of at leastone of the plurality of SAW filters except for the at least one SAWfilter connected to the first SPnT switch from among the plurality ofSAW filters, a SPDT switch connected to an input port of the first SPnTswitch and an input port of the second SPnT switch, a first combinerconnected to an output port of at least one of the plurality of SAWfilters, and a second combiner connected to an output port of at leastone of the plurality of SAW filters except for the at least one SAWfilter connected to the first combiner from among the plurality of SAWfilters.

In accordance with still another aspect of the present invention, aswitching circuit for selecting a frequency band is provided. Theswitching circuit includes a plurality of SAW filters, a first SPnTswitch connected to an input port of each of the plurality of SAWfilters, and a second SPnT switch connected to an output port of each ofthe plurality of SAW filters.

In accordance with still another aspect of the present invention, an RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a SPnT switch connected to an inputport of each of the plurality of SAW filters, and a DPnT switchconnected to an output port of each of the plurality of SAW filters.

In accordance with still another aspect of the present invention, an RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a SPnT switch connected to an inputport of each of the plurality of SAW filters, a first DPnT switchconnected to an output port of at least one of the plurality of SAWfilters, and a second DPnT switch connected to an output port of atleast one of the plurality of SAW filters except for the at least oneSAW filter connected to the first DPnT switch from among the pluralityof SAW filters.

In accordance with still another aspect of the present invention, a RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a SPnT switch connected to an inputport of each of the plurality of SAW filters, a second SPnT switchconnected to an output port of at least one of the plurality of SAWfilters, and a third SPnT switch connected to an output port of at leastone of the plurality of SAW filters except for the at least one SAWfilter connected to the second SPnT switch from among the plurality ofSAW filters.

In accordance with still another aspect of the present invention, an RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a first SPnT switch connected to aninput port of at least one of the plurality of SAW filters, a secondSPnT switch connected to an input port of at least one of the pluralityof SAW filters except for the at least one SAW filter connected to thefirst SPnT switch from among the plurality of SAW filters, a SPDT switchconnected to an input port of the first SPnT switch and input port ofthe second SPnT switch, and a combiner connected to an output port ofeach of the plurality of SAW filters.

In accordance with still another aspect of the present invention, an RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a first SPnT switch connected to aninput port of at least one of the plurality of SAW filters, a secondSPnT switch connected to an input port of at least one of the pluralityof SAW filters except for the at least one SAW filter connected to thefirst SPnT switch from among the plurality of SAW filters, a SPDT switchconnected to an input port of the first SPnT switch and an input port ofthe second SPnT switch, a first combiner connected to an output port ofat least one of the plurality of SAW filters, and a second combinerconnected to an output port of at least one of the plurality of SAWfilters except for the at least one SAW filter connected to the firstcombiner from among the plurality of SAW filters.

In accordance with still another aspect of the present invention, an RFhardware for selecting a frequency band is provided. The RF hardwareincludes a plurality of SAW filters, a first SPnT switch connected to aninput port of each of the plurality of SAW filters, and a second SPnTswitch connected to an output port of each of the plurality of SAWfilters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a SPnT switch connected to an input port of each of theplurality of SAW filters, and a DPnT switch connected to an output portof each of the plurality of SAW filters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a SPnT switch connected to an input port of each of theplurality of SAW filters, a DPnT switch connected to an output port ofat least one of the plurality of SAW filters, and a second DPnT switchconnected to an output port of at least one of the plurality of SAWfilters except for the at least one SAW filter connected to the firstDPnT switch from among the plurality of SAW filters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a first SPnT switch connected to an input port of eachof the plurality of SAW filters, a second SPnT switch connected to anoutput port of at least one of the plurality of SAW filters, and a thirdSPnT switch connected to an output port of at least one of the pluralityof SAW filters except for the at least one SAW filter connected to thesecond SPnT switch from among the plurality of SAW filters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a first SPnT switch connected to an input port of atleast one of the plurality of SAW filters, a second SPnT switchconnected to an input port of at least one of the plurality of SAWfilters except for the at least one SAW filter connected to the firstSPnT switch from among the plurality of SAW filters, a SPDT switchconnected to an input port of the first SPnT switch and input port ofthe second SPnT switch; and a combiner connected to an output port ofeach of the plurality of SAW filters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a first SPnT switch connected to an input port of atleast one of the plurality of SAW filters, a second SPnT switchconnected to an input port of at least one of the plurality of SAWfilters except for the at least one SAW filter connected to the firstSPnT switch from among the plurality of SAW filters, a SPDT switchconnected to an input port of the first SPnT switch and an input port ofthe second SPnT switch, a first combiner connected to an output port ofat least one of the plurality of SAW filters, and a second combinerconnected to an output port of at least one of the plurality of SAWfilters except for the at least one SAW filter connected to the firstcombiner from among the plurality of SAW filters.

In accordance with still another aspect of the present invention, an FEMfor selecting a frequency band is provided. The FEM includes a pluralityof SAW filters, a first SPnT switch connected to an input port of eachof the plurality of SAW filters, and a second SPnT switch connected toan output port of each of the plurality of SAW filters.

In accordance with still another aspect of the present invention, asignal reception apparatus for selecting a frequency band is provided.The signal reception apparatus includes a switching circuit, including aplurality of SAW filters, for integrating at least one of signals outputfrom the plurality of SAW filters based on a frequency band selectionsignal and outputting the integrated signal, and a controller forgenerating the frequency band selection signal which control theswitching circuit to integrate at least one of signals output from theplurality of SAW filters based on a frequency band to be used in thesignal reception apparatus and output the integrated signal.

In accordance with still another aspect of the present invention, amethod for selecting a frequency band in a signal reception apparatus isprovided. The method includes generating a frequency band selectionsignal indicating a frequency band to be selected if a frequency bandselection is necessary, and integrating at least one of signals outputfrom a plurality of SAW filters included in a switching circuit based onthe frequency band selection signal and outputting the integratedsignal.

In accordance with still another aspect of the present invention, amethod for selecting a frequency band in a switching circuit isprovided. The method includes integrating at least one of signals outputfrom a plurality of SAW filters included in a switching circuit based ona frequency band selection signal and outputting the integrated signal.

Other aspects, advantages, and salient features of the invention willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainexemplary embodiments of the present invention will be more apparentfrom the following description taken in conjunction with theaccompanying drawings, in which:

FIG. 1 illustrates an internal structure of an MS in a radiocommunication system according to the related art;

FIG. 2 illustrates an internal structure of a signal reception apparatusin a radio communication system according to an exemplary embodiment ofthe present invention;

FIG. 3 illustrates an example of an internal structure of a Front EndModule (FEM), such as the FEM 215 shown in FIG. 2, according to anexemplary embodiment of the present invention;

FIG. 4 illustrates another example of an internal structure of an FEM,such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention;

FIG. 5 illustrates further another example of an internal structure ofan FEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention;

FIG. 6 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention;

FIG. 7 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention;

FIG. 8 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention;

FIG. 9 is a flowchart illustrating an operation of a controller, such asthe controller 217 shown in FIG. 2, according to an exemplary embodimentof the present invention; and

FIG. 10 is a flowchart illustrating an operation of an FEM, such as theFEM 215 shown in FIG. 2, according to an exemplary embodiment of thepresent invention.

Throughout the drawings, it should be noted that like reference numbersare used to depict the same or similar elements, features, andstructures.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description with reference to the accompanying drawings isprovided to assist in a comprehensive understanding of exemplaryembodiments of the invention as defined by the claims and theirequivalents. It includes various specific details to assist in thatunderstanding but these are to be regarded as merely exemplary.Accordingly, those of ordinary skill in the art will recognize thatvarious changes and modifications of the embodiments described hereincan be made without departing from the scope and spirit of theinvention. In addition, descriptions of well-known functions andconstructions may be omitted for clarity and conciseness.

The terms and words used in the following description and claims are notlimited to the bibliographical meanings, but, are merely used by theinventor to enable a clear and consistent understanding of theinvention. Accordingly, it should be apparent to those skilled in theart that the following description of exemplary embodiments of thepresent invention is provided for illustration purpose only and not forthe purpose of limiting the invention as defined by the appended claimsand their equivalents.

It is to be understood that the singular forms “a,” “an,” and “the”include plural referents unless the context clearly dictates otherwise.Thus, for example, reference to “a component surface” includes referenceto one or more of such surfaces.

Exemplary embodiments of the present invention may include a switchingcircuit and a method for selecting a frequency band. Exemplaryembodiments of the present invention may also include Radio Frequency(RF) hardware and method for selecting a frequency band. Furthermore,exemplary embodiments of the present invention include a Front EndModule (FEM) and method for selecting a frequency band. Exemplaryembodiments of the present invention may also include a signal receptionapparatus and method for selecting a frequency band. Exemplaryembodiments of the present invention may include a switching circuit/RFhardware/FEM/signal reception apparatus and method for selecting afrequency band by combining output signals from filters. Exemplaryembodiments of the present invention may also include a switchingcircuit/RF hardware/FEM/signal reception apparatus and method forselecting a frequency band by combining output signal from filtersthereby satisfying a threshold frequency band attenuation requirementvalue. Exemplary embodiments of the present invention may furtherinclude a switching circuit/RF hardware/FEM/signal reception apparatusand method for selecting a frequency band by combining output signalfrom filters thereby satisfying a threshold isolation requirement value.

Exemplary embodiments of the present invention will be described belowwith reference to the FEM. However, it will be understood by those ofordinary skill in the art that the switching circuit, the RF hardware,and the signal reception apparatus as well as the FEM may select afrequency band in the same manner used in the FEM.

Exemplary embodiments of the present invention will be described belowwith reference to the filter, which may be a Surface Acoustic Wave (SAW)filter. However, it will be understood by those of ordinary skill in theart that the filter may be any one of other filters that are similarand/or suitable, as well as the SAW filter.

Furthermore, in exemplary embodiments of the present invention, it maybe assumed that a frequency band selection operation for each of theFEM, the switching circuit and the RF hardware may be described based ona signal reception apparatus. However, it will be understood by those ofordinary skill in the art that the frequency band selection operationfor each of the FEM, the switching circuit and the RF hardware may beapplied in a signal transmission apparatus.

Exemplary embodiments of the present invention will be described belowwith reference to the radio communication system, such as a Long-TermEvolution (LTE) mobile communication system. However, the radiocommunication system may be any one of a Long-Term Evolution Advanced(LTE-A) mobile communication system, an Evolved Packet System (EPS) andan Institute of Electrical and Electronics Engineers (IEEE) 802.16mmobile communication system or any other similar and/or suitable mobilecommunication system. Furthermore, in exemplary embodiments of thepresent invention, it is assumed that a signal reception apparatus maybe implemented in a Mobile Station (MS). However, the present inventionis not limited thereto, and the signal reception apparatus may be anysuitable electronic device.

FIG. 2 illustrates an internal structure of a signal reception apparatusin a radio communication system according to an exemplary embodiment ofthe present invention.

Referring to FIG. 2, the signal reception apparatus includes aModulator/Demodulator (MODEM) 211, a Radio Frequency Integrated Circuit(RFIC) 213, an FEM 215, a controller 217, and an antenna ANT. Thecontroller 217 may control the overall operation of the signal receptionapparatus, and may control the signal reception apparatus so as toperform an operation of combining output signals from SAW filtersincluded in the FEM 215. That is, the controller 217 may perform anoperation of combining output signals from SAW filters included in theFEM 215 based on a frequency band to be used.

The MODEM 211 may modulate a signal to be transmitted to a signaltransmission apparatus using a preset modulation scheme, such as a PhaseShift Keying scheme, a 16 Quadrature Amplitude Modulation (QAM) scheme,a 64 QAM scheme, or any other similar and/or suitable modulation scheme,and may output the modulated signal to the RFIC 213 under a control ofthe controller 217. The MODEM 211 may demodulate a signal received fromthe signal transmission apparatus using a demodulation schemecorresponding to a modulation scheme used in the signal transmissionapparatus, and may output the demodulated signal to the RFIC 213 under acontrol of the controller 217.

The RFIC 213 may convert a signal output from the MODEM 211 into an RFsignal and may output the RF signal to the FEM 215, or may convert asignal output from the FEM 215 into a baseband signal and may output thebaseband signal to the MODEM 211 under a control of the controller 217.The FEM 215 may perform a filtering operation on a signal output fromthe RFIC 213 and may transmit the filtered signal to a signal receptionapparatus through an antenna ANT, or may perform a filtering operationon a signal received through the antenna ANT and output the filteredsignal to the RFIC 213 under a control of the controller 217. The FEM215 may be implemented in various types, for example, a type including aswitch and SAW filters, and a type including the switch, a combiner, andthe SAW filters, or any other suitable and/or similar types, and thevarious types will be described below.

While the MODEM 211, the RFIC 213, the FEM 215, the controller 217 andthe antenna ANT are shown in FIG. 2 as separate units, it is to beunderstood that this is for merely convenience of description. In otherwords, the MODEM 211, the RFIC 213, the FEM 215, the controller 217 andthe antenna ANT may be incorporated into a single unit. An internalstructure of an FEM 215 shown in FIG. 2 will be described with referenceto FIGS. 3 to 8. That is, the FEM 215 shown in FIG. 2 may be implementedas one of exemplary embodiments shown in FIGS. 3 to 8.

FIG. 3 illustrates an example of an internal structure of an FEM, suchas the FEM 215 shown in FIG. 2, according to an exemplary embodiment ofthe present invention.

Referring to FIG. 3, the FEM 215 includes a Single-Pole 8 Throw (SP8T)switch 310, 8 SAW filters, such as SAW filters 320-1 through 320-8, anda Dual-Pole 16 Throw (DP16T) switch 330. The number of output ports ofthe FEM 215 is 1. An index mapped to an output port of each SAW filterdenotes a frequency band index of a frequency band used in a related SAWfilter, and the detailed description of the frequency band index will beomitted.

A threshold frequency band attenuation requirement value and a thresholdisolation requirement value used in the signal reception apparatusshould be satisfied after the signals output from the 8 SAW filters areintegrated in order to integrate the signals output from the 8 SAWfilters. In the present exemplary embodiments, it may be assumed thateach of the threshold frequency band attenuation requirement value andthe threshold isolation requirement value is 40 [dB]. However, thepresent invention is not limited thereto, and the threshold frequencyband attenuation requirement value and the threshold isolationrequirement value may be any suitable and/or similar value.

An isolation of a Single-Pole n-Throw (SPnT) switch affects anattenuation characteristic if signals output from SAW filters are simplyintegrated, and accordingly, the threshold frequency band attenuationrequirement value and the threshold isolation requirement value may notbe satisfied. Thus, a structure of an FEM implemented so as to includean SPnT switch and a Dual-Pole n-Throw (DPnT) switch are connected tothe front and the rear of SAW filters in order to satisfy a thresholdfrequency band attenuation requirement value and a threshold isolationrequirement value is illustrated in FIG. 3. That is, each of the SAWfilters 320-1 to 320-8 may be connected to the SP8T switch 310 and theDP16T switch 330. Thus, signals output from the SAW filters 320-1 to320-8 may be integrated through the DP16T switch 330 in a predeterminedformat for the signal reception apparatus. Here, the predeterminedformat may be determined under a control of the controller 217 oraccording to any suitable and/or similar manner.

The DP16T switch 330 may be used because the signals output from the SAWfilters 320-1 to 320-8 are balance signals. However, it will beunderstood by those of ordinary skill in the art that the DP16T switch330 may be an SPnT switch in a case where the signals output from theSAW filters 320-1 to 320-8 are single signals, and will be describedbelow with reference to FIG. 8. So, it is possible that the FEM 215 maybe in a form in which the threshold frequency band attenuationrequirement value and the threshold isolation requirement value aresatisfied because an isolation characteristic is acquired in the frontand the rear of SAW filters if the FEM 215 is implemented as describedwith reference to FIG. 3.

FIG. 4 illustrates another example of an internal structure of an FEM,such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention.

Referring to FIG. 4, the FEM 215 includes an SP8T switch 410, 8 SAWfilters including SAW filters 420-1 to 420-8, a DP6T switch 430, and aDP6T switch 440. An index mapped to an output port of each SAW filterdenotes a frequency band index of a frequency band used in a related SAWfilter, and the detailed description of the frequency band index will beomitted.

As described with reference FIG. 3, the FEM 215 in FIG. 4 may be alsoimplemented as a type in which an SPnT switch and a DPnT switch areconnected to the front and the rear of the SAW filters in order tosatisfy a threshold frequency band attenuation requirement value and athreshold isolation requirement value. That is, the SAW filters 420-2,420-3 and 420-4 may be connected to the SP8T switch 410 and the DP6Tswitch 430, and signals output from the SAW filters 420-2, 420-3 and420-4 may be integrated through the DP6T switch 430 in a predeterminedformat for the signal reception apparatus. The predetermined format maybe determined under a control of the controller 217 or according to anysuitable manner. That is, the SAW filters 420-5, 420-6, 420-7 and 420-8may be connected to the SP8T switch 410 and the DP8T switch 440, andsignals output from the SAW filters 420-5, 420-6, 420-7 and 420-8 may beintegrated through the DP8T switch 440 in a predetermined format for thesignal reception apparatus. Here, the predetermined format may bedetermined under a control of the controller 217 or according to anysuitable manner. A signal output from the SAW filter 420-1 is output asit is, and thus, may be not output through a DPnT switch.

The signal output from the SAW filter 420-1 may be a High frequency Band(HB) signal, a signal output from the DP6T switch 430 may be a Middlefrequency Band (MB) signal, and a signal output from the DP8T switch 440may be a Low frequency Band (LB) signal. That is, the FEM 215, asillustrated in FIG. 4, includes three output ports, i.e., an LB port, anMB port, and an HB port. The LB denotes a frequency band lower than afirst threshold frequency band, the MB denotes a frequency band equal toor greater than the first threshold frequency band and lower than asecond threshold frequency band, and the HB denotes a frequency bandequal to or greater than the second threshold frequency band.

The DP6T switch 430 and the DP8T switch 440 may be used because thesignals output from the SAW filters 420-1 to 420-8 are balance signals.However, it will be understood by those of ordinary skill in the artthat each of the DP6T switch 430 and the DP8T switch 440 may be an SPnTswitch in a case where the signals output from the SAW filters 420-1 to420-8 are single signals, and will be described below with reference toFIG. 7. As described above, the FEM 215 may be in a form in which thethreshold frequency band attenuation requirement value and the thresholdisolation requirement value are satisfied because an isolationcharacteristic may be acquired in the front and the rear of SAW filtersif the FEM 215 is implemented as described in FIG. 4.

FIG. 5 illustrates further another example of an internal structure ofan FEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention.

Referring to FIG. 5, the FEM 215 may include a Single-Pole Double Throw(SPDT) switch 510, an SP4T switch 520, an SP4T switch 530, 8 SAW filtersincluding SAW filters 540-1 to 540-8, and a combiner 550. As shown inFIG. 5, the number of output ports of the FEM 215 is 1. An index mappedto an output port of each SAW filter denotes a frequency band index of afrequency band used in a related SAW filter, and the detaileddescription of the frequency band index will be omitted.

Unlike the exemplary embodiments of FIGS. 3 to 4, the FEM 215 in FIG. 5may be implemented as a type in which an SPDT switch, which may acquirea relatively high isolation, and an SPnT switch are connected to thefront of SAW filters in order to satisfy a threshold frequency bandattenuation requirement value and a threshold isolation requirementvalue. The SPDT switch has a relatively low Insertion Loss (IL).Meanwhile, the SP4T switch may acquire relatively high isolation fromamong SPnT switches that are known to be used in radio communicationsystems, and the SPDT switch may be used in the exemplary embodiment ofFIG. 5 since the SP4T switch only supports 4 ports.

Thus, the SAW filters 540-1, 540-2, 540-3 and 540-4 may be connected tothe SP4T switch 520 and the combiner 550, and signals output from theSAW filters 540-1, 540-2, 540-3 and 540-4 may be integrated through thecombiner 550 in a predetermined format for the signal receptionapparatus. The predetermined format may be determined under a control ofthe controller 217 or according to any suitable manner.

The SAW filters 540-5, 540-6, 540-7, and 540-8 may be connected to theSP4T switch 530 and the combiner 550, and signals output from the SAWfilter 540-5, 540-6, 540-7, and 540-8 may be integrated through thecombiner 550 in a predetermined format for the signal receptionapparatus. The predetermined format may be determined under a control ofthe controller 217 or according to any suitable manner. Accordingly, theFEM 215 may be implemented such that the threshold frequency bandattenuation requirement value and the threshold isolation requirementvalue are satisfied because an isolation characteristic is acquired inthe front of SAW filters if the FEM 215 is implemented as described inFIG. 5.

FIG. 6 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention.

Referring to FIG. 6, the FEM 215 may include an SPDT switch 610, an SP4Tswitch 620, an SP4T switch 630, 8 SAW filters including SAW filters640-1 to 640-8, a combiner 650 and a combiner 660. An index mapped to anoutput port of each SAW filter denotes a frequency band index of afrequency band used in a related SAW filter, and the detaileddescription of the frequency band index will be omitted. As described inFIG. 5, the FEM 215 in FIG. 6 may be a type in which an SPDT switch,which may acquire a relatively high isolation, and an SPnT switch areconnected to the front of SAW filters in order to satisfy a thresholdfrequency band attenuation requirement value and a threshold isolationrequirement value.

Accordingly, the SAW filters 640-2, 640-3, and 640-4 may be connected tothe SP4T switch 620 and the combiner 650, and signals output from theSAW filter 640-2, the SAW filter 640-3 and the SAW filter 640-4 may beintegrated through the combiner 650 in a predetermined format for thesignal reception apparatus. The predetermined format may be determinedunder a control of the controller 217 or according to any suitablemanner. The SAW filters 640-5, 640-6, 640-7, and 640-8 may be connectedto the SP4T switch 630, and signals output from the SAW filters 640-5,640-6, 640-7, and 640-8 may be integrated through the combiner 660 in apredetermined format for the signal reception apparatus. Thepredetermined format may be determined under a control of the controller217 or according to any suitable manner.

A signal output from the SAW filter 640-1 may be output as it is ratherthan being output through a combiner. The signal output from the SAWfilter 640-1 may be output as an HB signal, a signal output from thecombiner 650 may be output as an MB signal, and a signal output from thecombiner 660 may be output as an LB signal. That is, the FEM 215according to the exemplary embodiment of FIG. 6 includes 3 output ports,i.e., an LB port, an MB port, and an HB port. Accordingly, the FEM 215may be a form in which the threshold frequency band attenuationrequirement value and the threshold isolation requirement value aresatisfied because an isolation characteristic is acquired in the frontof SAW filters if the FEM 215 is implemented as described in FIG. 6.

FIG. 7 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention.

Referring to FIG. 7, the FEM 215 includes an SP8T switch 710, 8 SAWfilters including SAW filters 720-1 to 720-8, an SP4T switch 730 and anSP4T switch 740. An index mapped to an output port of each SAW filterdenotes a frequency band index of a frequency band used in a related SAWfilter, and the detailed description of the frequency band index will beomitted.

The FEM 215 according to the exemplary embodiment of FIG. 7 may beimplemented as a type in which a SPnT switch is connected to the frontand the rear of SAW filters in order to satisfy a threshold frequencyband attenuation requirement value and a threshold isolation requirementvalue. That is, the SAW filters 720-2, 720-3, and 720-4 may be connectedto the SP8T switch 710 and the SP4T switch 730, and signals output fromthe SAW filters 720-2, 720-3, and 720-4 may be integrated through theSP4T switch 730 according to a predetermined format for the signalreception apparatus. The predetermined format may be determined under acontrol of the controller 217 or according to any suitable manner. Thatis, the SAW filters 720-5, 720-6, 720-7, and 720-8 may be connected tothe SP8T switch 710 and the SP4T switch 740, and signals output from theSAW filters 720-5, 720-6, 720-7, and 720-8 may be integrated through theSP4T switch 740 in a predetermined format for the signal receptionapparatus. The predetermined format is determined under a control of thecontroller 217. The predetermined format may be determined under acontrol of the controller 217 or according to any suitable manner. Asignal output from the SAW filter 420-1 may be output as it is ratherthan being output through an SP4T switch.

The signal output from the SAW filter 720-1 may be output as an HBsignal, a signal output from the SP4T switch 730 may be output as an MBsignal, and a signal output from the SP4T switch 740 may be output as anLB signal. That is, the FEM 215 according to the exemplary embodimentFIG. 7 may include 3 output ports, i.e., an LB port, an MB port, and anHB port.

The SP4T switch 730 and the SP4T switch 740 may be used because thesignals output from the SAW filters 720-2 to 720-8 are single signals.As described in FIG. 1, it will be understood by those of ordinary skillin the art that each of the SP4T switch 730 and the SP4T switch 740 maybe a DPnT switch in a case where the signals output from the SAW filters720-2 to 720-8 are balance signals. Thus, the FEM 215 may be a form inwhich the threshold frequency band attenuation requirement value and thethreshold isolation requirement value are satisfied because an isolationcharacteristic is acquired in the front and the rear of SAW filters ifthe FEM 215 is implemented as described with respect to FIG. 7.

FIG. 8 illustrates still another example of an internal structure of anFEM, such as the FEM 215 shown in FIG. 2, according to an exemplaryembodiment of the present invention.

Referring to FIG. 8, the FEM 215 includes an SP8T switch 810, 8 SAWfilters including SAW filters 820-1 to 820-8, and an SP8T switch 830.So, the number of output ports of the FEM 215 is 1. An index mapped toan output port of each SAW filter denotes a frequency band index of afrequency band used in a related SAW filter, and the detaileddescription of the frequency band index will be omitted.

The FEM 215 according to the exemplary embodiment FIG. 8 may beimplemented as a type in which a SPnT switch is connected to the frontand the rear of SAW filters in order to satisfy a threshold frequencyband attenuation requirement value and a threshold isolation requirementvalue. That is, each of the SAW filters 820-1 to 820-8 may be connectedto the SP8T switch 810 and the SP8T switch 830. Signals output from theSAW filters 820-1 to 820-8 may be integrated through the SP8T switch 830in a predetermined format for the signal reception apparatus. Thepredetermined format may be determined under a control of the controller217 or according to any suitable manner.

The SP8T switch 830 may be used because the signals output from the SAWfilters 820-1 to 820-8 are single signals. As described with referenceto FIG. 3, it will be understood by those of ordinary skill in the artthat each of the SP8T switch 830 may be changed to a DPnT switch if thesignals output from the SAW filters 820-1 to 820-8 are balance signals.

FIG. 9 is a flowchart illustrating an operation of a controller, such asthe controller 217 shown in FIG. 2, according to an exemplary embodimentof the present invention.

Referring to FIG. 9, a controller 217 initially controls an FEM 215 tointegrate signals output from SAW filters included in the FEM 215 inoperation 911, and detects a need for selecting a frequency band to beused in a signal reception apparatus in operation 913. There may be manycases in which the need for selecting the frequency band to be used inthe signal reception apparatus is detected, for example, a case that aMODEM is initialized, a case that a specific mode is used in the MODEM,a case that multi-carriers are used, and any other similar and orsuitable case, and the detailed description thereof will be omittedherein. The controller 217 generates a frequency band selection signalindicating a frequency band to be selected in operation 915 andtransmits the frequency band selection signal to the FEM 215 inoperation 917. After receiving the frequency band selection signal, theFEM 215 integrates signals output from SAW filters included in the FEM215 based on the band selection signal and outputs the integratedsignal.

FIG. 10 is a flowchart illustrating an operation of an FEM, such as theFEM 215 shown in FIG. 2, according to an exemplary embodiment of thepresent invention.

Referring to FIG. 10, an FEM 215 receives a frequency band selectionsignal from a controller 217 in operation 1011, and generates afrequency band based on the frequency band selection signal bycontrolling a connection among SAW filters, at least one switch and/orat least one combiner included in the FEM 215 in operation 1013. Theoperation of generating the frequency band the FEM 215 is performed inthe manner described before with reference to FIGS. 3 to 8, so thedetailed description will be omitted herein.

As is apparent from the foregoing description, exemplary embodiments ofthe present invention enable integrating signals output from SAW filtersin an FEM in a signal reception apparatus. Exemplary embodiments of thepresent invention enable integrating signals output from SAW filters inan FEM in a signal reception apparatus in order to satisfy a thresholdfrequency band attenuation requirement value. Exemplary embodiments ofthe present invention enable integrating of the signals output from theSAW filters in the FEM in the signal reception apparatus in order tosatisfy a threshold isolation requirement value.

Exemplary embodiments of the present invention enable integrating thesignals output from the SAW filters in the FEM in the signal receptionapparatus, thereby decreasing the unit cost of production without pathson which the SAW filters and an RFIC are connected in a one to onemanner. Exemplary embodiments of the present invention enableintegrating the signals output from the SAW filters in the FEM in thesignal reception apparatus, thereby minimizing a hardware space in thesignal reception apparatus without the paths on which the SAW filtersand the RFIC are connected one to one.

While the invention has been shown and described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that various changes in form and details may be madetherein without departing from the spirit and scope of the invention asdefined by the appended claims and their equivalents.

What is claimed is:
 1. A switching circuit for selecting a frequencyband, the switching circuit comprising: a plurality of surface acousticwave (SAW) filters corresponding to frequency bands; a first switch,connected to an input port of each of the plurality of SAW filters, andconnected to an antenna circuit; and a second switch, connected to anoutput port of each of the plurality of SAW filters, the second switchhaving an output port outputting at least two signals filtered by theplurality of SAW filters, based on at least one of a threshold frequencyband attenuation requirement value or a threshold isolation requirementvalue.
 2. The switching circuit as claimed in claim 1, wherein the firstswitch is a single-pole n throw (SPnT) switch, the second switch is adual-pole n throw (DPnT) switch, and n is an integer.
 3. The switchingcircuit as claimed in claim 1, wherein the output port of the secondswitch is connected to a radio frequency integrated circuit (RFIC). 4.The switching circuit as claimed in claim 1, wherein the first switchand the second switch are controlled by at least one processorconfigured to output the at least two signals filtered from theplurality of SAW filters, based on the threshold isolation requirementvalue.
 5. The switching circuit as claimed in claim 1, wherein the firstswitch and the second switch are controlled by at least one processorconfigured to output the at least two signals filtered from theplurality of SAW filters, based on the threshold frequency bandattenuation requirement value.
 6. The switching circuit as claimed inclaim 1, wherein the signal output from each of the plurality of SAWfilters is a balance signal.
 7. A mobile station for selecting afrequency band, the mobile station comprising: an antenna circuit; afront end module (FEM) connected to the antenna circuit; and a radiofrequency integrated circuit (RFIC) connected to the FEM, wherein theFEM comprises: a plurality of surface acoustic wave (SAW) filterscorresponding to frequency bands, a first switch connected to an inputport of each of the plurality of SAW filters, and connected to theantenna circuit, and a second switch, connected to an output port ofeach of the plurality of SAW filters, the second switch having an outputport outputting at least two signals filtered by the plurality of SAWfilters, based on at least one of a threshold frequency band attenuationrequirement value or a threshold isolation requirement value.
 8. Themobile station as claimed in claim 7, wherein the first switch is asingle-pole n throw (SPnT) switch, the second switch is a dual-pole nthrow (DPnT) switch, and n is an integer.
 9. The mobile station asclaimed in claim 7, wherein the output port of the second switch isconnected to the RFIC.
 10. The mobile station as claimed in claim 7,further comprising at least one processor configured to control thefirst switch and the second switch to output the at least two signalsfiltered from the plurality of SAW filters, based on the thresholdisolation requirement value.
 11. The mobile station as claimed in claim7, further comprising at least one processor configured to control thefirst switch and the second switch to output the at least two signalsfiltered from the plurality of SAW filters, based on the thresholdfrequency band attenuation requirement value.
 12. The mobile station asclaimed in claim 7, wherein the signal output from each of the pluralityof SAW filters is a balance signal.